When your mom told you not to pee in the ocean, it could just be because she didn't want lovesick female swordtail fish flocking to you. Male swordtail urine may be full of pheromones that drive the ladies crazy, researchers report[2] today in PLoS ONE. By injecting swordtails with a fluorescent dye that makes their urine glow under ultraviolet light in an aquarium, the team found that males were more likely to leave a warm spot just upstream of where the females were gathered. Chemical communication in fish and other undersea creatures hasn't been extensively studied, but if toxins in the water garble these important signals, they could disrupt fish reproduction and harm marine ecology. So while it may be bad manners to pee in the sea, it's even worse to pollute it.